Gas Exchange In Patients Research Articles

Lung morphology and surfactant function in cardiogenic pulmonary edema: a narrative review.

The conventional analysis of acute cardiogenic pulmonary edema involves the development of high pulmonary capillary pressures resulting in hydrostatic gradients for fluid flux out of capillaries into the interstitial space and alveolar spaces. However, some patients respond poorly to diuretic management. The PubMed database was searched to identify experimental studies on pulmonary edema in animals, experimental studies on surfactant function, including patients with pulmonary edema, and clinical studies reporting barrier dysfunction and/or injury in patients with acute pulmonary edema. Studies with animal models demonstrate that high capillary pressures can cause barrier disruption in alveolar capillary units which increases permeability and the transfer of fluid and protein into lung parenchyma. Fluid in alveolar spaces alters surfactant function which increases fluid flux out of capillaries into the lung parenchyma secondary to larger transcapillary hydrostatic gradients. Patients with acute cardiogenic pulmonary edema have increased levels of surfactant protein B in their plasma which reflect barrier disruption and increased levels of tumor necrosis factor alpha which reflect acute tissue injury. Increased surfactant protein B plasma levels are associated with abnormal gas exchange in patients with chronic heart failure. Patients with exercise-induced left ventricular dysfunction have increased levels of surfactant protein B after short periods of exercise. Pathology studies in patients with chronic heart failure have found increased connective tissue in alveolar capillary units and increased numbers of type II alveolar cells, and these changes represent an adaptive response in these patients. Clinicians need to consider the possibility of barrier dysfunction and disruption in patients with both acute and chronic pulmonary edema and understand that diuresis may have a limited effect on symptoms in some patients.

Pulmonary Vascular Distensibility and Early Pulmonary Vascular Remodeling in Pulmonary Hypertension

Exercise stress testing of the pulmonary circulation may uncover decreased pulmonary vascular (PV) distensibility as a cause of impaired aerobic exercise capacity and right ventricular (RV)-pulmonary arterial (PA) uncoupling. As such, it may help in the differential diagnosis of unexplained dyspnea, including pulmonary hypertension (PH) and/or heart failure with preserved ejection fraction (HFpEF). We investigated rest and exercise invasive pulmonary hemodynamics, ventilation, and gas exchange in patients with unexplained dyspnea, including 44 patients with HFpEF (of whom 20 had a normal pulmonary vascular resistance [PVR] during exercise [ie, passive HFpEF] and 24 had a higher than normal exercise PVR), 22 patients with exercise PH, 19 patients with pulmonary arterial hypertension (PAH), and 24 age- and sex-matched normal control subjects. A PV distensibility coefficient α (%/mmHg) was determined from multipoint PV pressure-flow plots. RV-PA coupling was quantified from the analysis of RV pressure curves to determine ratios of end-systolic to arterial elastances (Ees/Ea). Aerobic exercise capacity was estimated by peak oxygen consumption. The α coefficient decreased from 1.35 ± 0.58%/mmHg in control subjects and 1.1 ± 0.48%/mmHg in patients with passive HFpEF to 0.62 ± 0.32%/mmHg in exercise PH, 0.54 ± 0.27%/mmHg in HFpEF with high exercise PVR, and 0.18 ± 0.16%/mm Hg in PAH. On multivariate analysis, PV distensibility was associated with decreased Ees/Ea and maximal volume of oxygen consumed. PV distensibility is an early and sensitive hemodynamic marker of PV disease that is associated with RV-PA uncoupling and decreased aerobic exercise capacity.

Dynamic airway constriction in rats: heterogeneity and response to deep inspiration.

Airway narrowing due to hyperresponsiveness severely limits gas exchange in patients with asthma. Imaging studies in humans and animals have shown that bronchoconstriction causes patchy patterns of ventilation defects throughout the lungs, and several computational models have predicted that these regions are due to constriction of smaller airways. However, these imaging approaches are often limited in their ability to capture dynamic changes in small airways, and the patterns of constriction are heterogeneous. To directly investigate regional variations in airway narrowing and the response to deep inspirations (DIs), we utilized tantalum dust and microfocal X-ray imaging of rat lungs to obtain dynamic images of airways in an intact animal model. Airway resistance was simultaneously measured using the flexiVent system. Custom-developed software was used to track changes in airway diameters up to generation 19 (~0.3-3 mm). Changes in diameter during bronchoconstriction were then measured in response to methacholine (MCh) challenge. In contrast with the model predictions, we observed significantly greater percent constriction in larger airways in response to MCh challenge. Although there was a dose-dependent increase in total respiratory resistance with MCh, the percent change in airway diameters was similar for increasing doses. A single DI following MCh caused a significant reduction in resistance but did not cause a significant increase in airway diameters. Multiple DIs did, however, cause significant increases in airway diameters. These measurements allowed us to directly quantify dynamic changes in airways during bronchoconstriction and demonstrated greater constriction in larger airways.

Airway Procedures

There has been a marked increase in the number and complexity of airway procedures performed both in the operating room and procedural areas. The anesthesiologist is challenged with establishing a patent shared airway and maintaining adequate gas exchange in patients with compromised airways and/or respiratory function. This review presents a general approach to the patient presenting for an airway procedure and highlights the commonly occurring complications. Airway fire, bleeding, and airway disruption or obstruction may occur. Some of the newer interventional bronchoscopic procedures are introduced, with emphasis on anesthetic implications. A more detailed discussion surrounds the anesthetic management of central airway obstruction and airway stenting. This review contains 8 figures, 5 tables, 30 references. Key Words: anesthesia for flexible bronchoscopy, anesthesia for rigid bronchoscopy, airway stenting, bronchoscopy, central airway obstruction, interventional pulmonology, total intravenous anesthesia, ventilation

Effect of PEEP-Induced Alveolar Recruitment on Lung Injury during Extracorporeal Membrane Oxygenation for ARDS

Purpose Extracorporeal membrane oxygenation, veno-venous configuration (VV-ECMO) is an effective intervention to improve gas exchange in patients with severe respiratory failure, refractory to conventional treatments, or as a bridge to lung transplantation. However, optimal mechanical ventilation (MV) strategies during VV-ECMO to minimize ventilator-induced lung injury are undetermined. While there is general consensus in minimizing tidal ventilation, the potential benefit of high positive end-expiratory pressure (PEEP) strategies in optimizing cardiopulmonary interaction and reducing the severity of lung injury remains unclear.We hypothesize that PEEP-induced alveolar recruitment will reduce lung injury during VV-ECMO for ARDS, in comparison to atelectatic lungs. Methods Yorkshire pigs weresedated, paralyzed, mechanically ventilated,and cannulated for VV-ECMO support. Lung injury was done by two serial bronchoscopic instillations of gastric juice to achieve a P/F ratio Results During VV-ECMO, gas exchange and hemodynamic parameters remained stable and comparable in the two groups, despite the very low tidal volume delivered (HP 54 ml ±; LP 41 ml ±11). Lung volume was higher in the HP compared with the LP group, and remained unchanged during the 5 hours of VV-ECMO support. At the end of the 5 hours of ECMO support, in the dependent lung areas the W/D was significantly higher in the HP compared to LP group (HP 11.1, 95% CI: 10.5-11.7; LP 9.2, 95% CI: 8.2-10.3); in the non-dependent areas the W/D was significantly higher in the LP compared to HP group (LP 6.3, 95% CI: 5.6-6.9; HP 5.3, 95% CI: 4.9-5.8). Conclusion VV-ECMO for severe acute respiratory failure MV with very low tidal volume and LP reduces regional lung edema in the dependent areas, while HP reduces edema.More studies are required to characterize the mechanisms of these findings.

Go West: translational physiology for noninvasive measurement of pulmonary gas exchange in patients with hypoxemic lung disease.

Go West: translational physiology for noninvasive measurement of pulmonary gas exchange in patients with hypoxemic lung disease.

Effect of Transjugular Intrahepatic Portosystemic Shunt Creation on Pulmonary Gas Exchange in Patients with Hepatopulmonary Syndrome: A Prospective Study

PurposeTo evaluate effect of transjugular intrahepatic portosystemic shunt (TIPS) creation on pulmonary gas exchange in patients with hepatopulmonary syndrome (HPS). Materials and MethodsAll patients with cirrhosis or Budd-Chiari syndrome undergoing elective TIPS creation at a single institution between June 2014 and June 2015 were eligible for inclusion. Twenty-three patients with HPS (age 55.0 y ± 14.4; 11 men; Model for End-Stage Liver Disease score 10.2 ± 2.7) who achieved technical success were included in the analysis. Diagnosis of HPS was established by contrast-enhanced echocardiography demonstrating intrapulmonary vascular dilatation and arterial blood gas analysis demonstrating arterial oxygenation defects. ResultsMean portosystemic gradient was reduced from 21.7 mm Hg ± 8.3 before TIPS creation to 10.8 mm Hg ± 5.1 after TIPS creation. Among the 5 (21.7%) patients who experienced dyspnea, 4 (80.0%) reported improvement after TIPS creation. This improvement was not maintained at 3 months after TIPS creation in 2 (50.0%) patients. Compared with before TIPS creation, mean change in alveolar-arterial oxygen gradient for patients with HPS was statistically significant at 1 month (−9.2 mm Hg ± 8.0; P < .001) after TIPS creation, but not at 2–3 days (−0.9 mm Hg ± 10.5; P = .678) or 3 months (−3.4 mm Hg ± 11.8; P = .179) after TIPS creation. ConclusionsTIPS creation can transiently improve pulmonary gas exchange in patients with HPS.

Impact of Lung Expansion Therapy Using Positive End-Expiratory Pressure in Mechanically Ventilated Patients Submitted to Coronary Artery Bypass Grafting.

ObjectiveTo evaluate the impact of different levels of positive end-expiratory pressure (PEEP) on gas exchange in patients undergoing coronary artery bypass grafting (CABG).MethodsA randomized clinical trial was conducted with patients undergoing CABG surgery. Patients were randomized into three groups: Group 10, PEEP of 10 cmH2O; Group 12, PEEP of 12 cmH2O; and Group 15, PEEP of 15 cmH2O. After the randomization, all patients underwent gas analysis at three moments: (1) before lung expansion therapy (LET); (2) 30 minutes after LET; and (3) one hour after extubation.ResultsSixty-six patients were studied, of which 61.7% were men, with mean age of 64 ± 8.9 years. Patients allocated to Group 15 showed a significant improvement in gas exchange comparing pre- and post-expansion values (239±21 vs. 301±19, P<0,001) and the increase was maintained after extubation (278±26). Despite the use of high levels of PEEP, no significant hemodynamic change was evidenced.ConclusionIt is concluded that high levels of PEEP (15 cmH2O) are beneficial for the improvement of gas exchange in patients undergoing CABG.

Airway Procedures

There has been a marked increase in the number and complexity of airway procedures performed both in the operating room and procedural areas. The anesthesiologist is challenged with establishing a patent shared airway and maintaining adequate gas exchange in patients with compromised airways and/or respiratory function. This review presents a general approach to the patient presenting for an airway procedure and highlights the commonly occurring complications. Airway fire, bleeding, and airway disruption or obstruction may occur. Some of the newer interventional bronchoscopic procedures are introduced, with emphasis on anesthetic implications. A more detailed discussion surrounds the anesthetic management of central airway obstruction and airway stenting. This review contains 8 figures, 5 tables, 30 references. Key Words: anesthesia for flexible bronchoscopy, anesthesia for rigid bronchoscopy, airway stenting, bronchoscopy, central airway obstruction, interventional pulmonology, total intravenous anesthesia, ventilation

Effects of lowering inspiratory oxygen fraction during microvascular decompression on postoperative gas exchange: A pre-post study.

BackgroundDespite many previous studies, the optimal oxygen fraction during general anesthesia remains controversial. This study aimed to evaluate the effects of lowering intraoperative fraction of inspired oxygen on postoperative gas exchange in patients undergoing microvascular decompression (MVD).MethodsWe conducted a pre-post study to compare postoperative gas exchange with different intraoperative oxygen fractions. From April 2010 to June 2017, 1456 consecutive patients who underwent MVD were enrolled. Starting in January 2014, routine oxygen fraction was lowered from 1.0 to 0.3 during anesthetic induction/awakening and from 0.5 to 0.3 during anesthetic maintenance. Postoperative gas exchange, presented as the minimum value of PaO2/FIO2 ratio within 48 hours, were compared along with adverse events.ResultsAmong 1456 patients, 623 (42.8%) patients were stratified into group H (high FIO2) and 833 (57.2%) patients into group L (low FIO2). Intraoperative positive end-expiratory pressure was used in 126 (15.1%) patients in group H and 90 (14.4%) patients in group L (p = 0.77).The minimum value of PaO2/ FIO2 ratio within 48 hours after surgery was significantly greater in the group L (226.13 vs. 323.12; p < 0.001) without increasing any adverse events.ConclusionIn patients undergoing MVD, lowering routine FIO2 and avoiding 100% O2 improved postoperative gas exchange.

Should we titrate ventilation based on driving pressure? Maybe not in the way we would expect

Mechanical ventilation maintains adequate gas exchange in patients during general anaesthesia, as well as in critically ill patients without and with acute respiratory distress syndrome (ARDS). Optimization of mechanical ventilation is important to minimize ventilator induced lung injury and improve outcome. Tidal volume (VT), positive end-expiratory pressure (PEEP), respiratory rate (RR), plateau pressures as well as inspiratory oxygen are the main parameters to set mechanical ventilation. Recently, the driving pressure (∆P), i.e., the difference of the plateau pressure and end-expiratory pressure of the respiratory system or of the lung, has been proposed as a key role parameter to optimize mechanical ventilation parameters. The ∆P depends on the VT as well as on the relative balance between the amount of aerated and/or overinflated lung at end-expiration and end-inspiration at different levels of PEEP. During surgery, higher ∆P, mainly due to VT, was progressively associated with an increased risk to develop post-operative pulmonary complications; in two large randomized controlled trials the reduction in ∆P by PEEP did not result in better outcome. In non-ARDS patients, ∆P was not found even associated with morbidity and mortality. In ARDS patients, an association between ∆P (higher than 13-15 cmH2O) and mortality has been reported. In several randomized controlled trials, when ∆P was minimized by the use of higher PEEP with or without recruitment manoeuvres, this strategy resulted in equal or even higher mortality. No clear data are currently available about the interpretation and clinical use of ∆P during assisted ventilation. In conclusion, ∆P is an indicator of severity of the lung disease, is related to VT size and associated with complications and mortality. We advocate the use of ∆P to optimize individually VT but not PEEP in mechanically ventilated patients with and without ARDS.

Inhaled sGC Modulator Can Lower PH in Patients With COPD Without Deteriorating Oxygenation.

This study uses a highly fidelity computational simulator of pulmonary physiology to evaluate the impact of a soluble guanylate cyclase (sGC) modulator on gas exchange in patients with chronic obstructive pulmonary disease (COPD) and pulmonary hypertension (PH) as a complication. Three virtual patients with COPD were configured in the simulator based on clinical data. In agreement with previous clinical studies, modeling systemic application of an sGC modulator results in reduced partial pressure of oxygen (PaO2) and increased partial pressure of carbon dioxide (PaCO2) in arterial blood, if a drug‐induced reduction of pulmonary vascular resistance (PVR) equal to that observed experimentally is assumed. In contrast, for administration via dry powder inhalation (DPI), our simulations suggest that the treatment results in no deterioration in oxygenation. For patients under exercise, DPI administration lowers PH, whereas oxygenation is improved with respect to baseline values.

An opportunity to improve pulmonary capillary circulation in patients with chronic obstructive pulmonary disease and comorbidity

This study was aimed at investigating pathogenesis of pulmonary vascular abnormalities in COPD with systemic features, and ways to treat these circulatory disorders. Methods. We analyzed pulmonary vascular parameters, molecular markers of endothelial dysfunction, pulmonary artery pressure (PAP) and gas exchange in patients with moderate (n = 64) and severe (n = 70) COPD treated with basic therapy with or without an endothelial protector. Results. The results showed that perfusion disorders could appear in different parts of the lungs, probably, due to different mechanisms of these abnormalities. Localization of perfusion disorders was related to blood levels of molecular markers of endothelial dysfunction: adhesion molecules sP-selectin and sVCAM-1 were related to perfusion abnormalities in the upper lobes, VEGF-A was related to perfusion abnormalities in the lower lobes, and diffuse perfusion abnormalities were related to endothelin-1. Additional treatment with sulodexide improved endothelial function and pulmonary circulation, decreased PAP and blood concentrations of molecular markers of endothelial dysfunction. Conclusion. Predominant localization of microcirculatory abnormalities in COPD patients, especially in the lower lobes, is related to ventilation abnormalities, could predict clinical course of the disease and indicates the need in endotheliotropic therapy.

A New, Noninvasive Method of Measuring Impaired Pulmonary Gas Exchange in Lung Disease: An Outpatient Study

It would be valuable to have a noninvasive method of measuring impaired pulmonary gas exchange in patients with lung disease and thus reduce the need for repeated arterial punctures. This study reports the results of using a new test in a group of outpatients attending a pulmonary clinic. Inspired and expired partial pressure of oxygen (PO2) and Pco2 are continually measured by small, rapidly responding analyzers. The arterial PO2 is calculated from the oximeter blood oxygen saturation level and the oxygen dissociation curve. The PO2 difference between the end-tidal gas and the calculated arterial value is called the oxygen deficit. Studies on 17 patients with a variety of pulmonary diseases are reported. The mean ± SE oxygen deficit was 48.7 ± 3.1mmHg. This finding can be contrasted with a mean oxygen deficit of 4.0 ± 0.88mmHg in a group of 31 normal subjects who were previously studied (P< .0001). The analysis emphasizes the value of measuring the composition of alveolar gas in determining ventilation-perfusion ratio inequality. This factor is largely ignored in the classic index of impaired pulmonary gas exchange using the ideal alveolar PO2 to calculate the alveolar-arterial oxygen gradient. The results previously reported in normal subjects and the present studies suggest that this new noninvasive test will be valuable in assessing abnormal gas exchange in the clinical setting.

Measurements of pulmonary gas exchange efficiency using expired gas and oximetry: results in normal subjects.

We are developing a novel, noninvasive method for measuring the efficiency of pulmonary gas exchange in patients with lung disease. The patient wears an oximeter, and we measure the partial pressures of oxygen and carbon dioxide in inspired and expired gas using miniature analyzers. The arterial Po2 is then calculated from the oximeter reading and the oxygen dissociation curve, using the end-tidal Pco2 to allow for the Bohr effect. This calculation is only accurate when the oxygen saturation is <94%, and therefore, these normal subjects breathed 12.5% oxygen. When the procedure is used in patients with hypoxemia, they breathe air. The Po2 difference between the end-tidal and arterial values is called the "oxygen deficit." Preliminary data show that this index increases substantially in patients with lung disease. Here we report measurements of the oxygen deficit in 20 young normal subjects (age 19 to 31 yr) and 11 older normal subjects (47 to 88 yr). The mean value of the oxygen deficit in the young subjects was 2.02 ± 3.56 mmHg (means ± SD). This mean is remarkably small. The corresponding value in the older group was 7.53 ± 5.16 mmHg (means ± SD). The results are consistent with the age-related trend of the traditional alveolar-arterial difference, which is calculated from the calculated ideal alveolar Po2 minus the measured arterial Po2. That measurement requires an arterial blood sample. The present study suggests that this noninvasive procedure will be valuable in assessing the degree of impaired gas exchange in patients with lung disease.

Effect of inhaled iloprost on gas exchange in inhalation injury

ObjectiveInhalation injury is an independent risk factor for mortality in burn patients. The purpose of this study was to observe the effect of inhaled iloprost on gas exchange in patients with inhalation injury and acute respiratory failure as measured by an improved PaO2/FiO2 ratio. MethodsPatients admitted to the burn intensive care unit from 2013 to 2014 meeting Berlin criteria for acute respiratory distress syndrome (ARDS) with a diagnosis of inhalation injury and who received inhaled iloprost were included. Medical records were reviewed to collect patient demographics, characterize iloprost prescribing practices, and observe changes in oxygenation and hemodynamic status after iloprost administration. Differences were evaluated using a t-test with cluster corrected standard errors. ResultsA total of eight patients were included with 157 different PaO2/FiO2 ratios calculated. All patients had moderate or severe ARDS with a baseline PaO2/FiO2 ratio of 131.9mmHg (IQR 119.3–197.3). Median duration of iloprost therapy was 5days (IQR±7). A statistically significant increase in PaO2/FiO2 ratio was observed after iloprost administration with a mean increase of 9.7mmHg (95% CI 1.8–17.7, p=0.023). Inhaled iloprost had no effect on hemodynamic parameters. ConclusionsInhaled iloprost for inhalation injury and ARDS after burn injury was associated with a small but statistically significant improvement in oxygenation.

Prone positioning as a bridge to recovery from refractory hypoxaemia following lung transplantation.

Refractory hypoxaemia is the leading cause of mortality in the postoperative period after lung transplantation. The role of prone positioning as a rescue therapy in this setting has not been assessed. We evaluated its effects in lung transplant recipients presenting refractory hypoxaemia following the surgery. Prospectively collected data from 131 consecutive adult patients undergoing lung transplantation between January 2013 and December 2014 were evaluated. Twenty-two patients received prone position therapy. Indications, associated complications, time to initiation and duration of the manoeuvre were analysed and the effects of prone position on gas exchange were evaluated. Finally, outcomes in this cohort were compared against the rest of lung transplant recipients. Prone positioning was more frequently implemented within the first 72 h (68.2%) and its main indication was primary graft dysfunction. The manoeuvre was maintained during a median of 21 h. After prone position, the pressure of arterial oxygen/fraction of inspired oxygen ratio significantly increased from 81.0 mmHg [interquartile range (IQR) 71.5-104.0] to 220.0 (IQR 160.0-288.0) (P < 0.001). No complications related with the technique were reported. Patients who underwent the manoeuvre had longer hospital stay [50.0 days (IQR 36.0-67.0) vs 30.0 (IQR 23.0-56.0), P = 0.006] than the rest of the population. No differences were found comparing either 1-year mortality (9.1% vs 15.6%; P = 0.740) or 1-year graft function [forced expiratory volume in 1 second of 70.0 (IQR 53.0-83.0) vs 68.0 (IQR 53.5-80.5), P = 0.469]. Prone positioning is safe and significantly improves gas exchange in patients with refractory hypoxaemia after lung transplantation. It should be considered as a possible treatment in these patients.

Effect of non-invasive NAVA on the patients with acute exacerbation of chronic obstructive pulmonary disease

Objective: To observe the effect of non-invasive neurally adjusted ventilatory assist (NIV-NAVA) on patient-ventilator synchrony and effect of gas exchange in patients with acute exacerbation of chronic obstructive pulmonary disease compared with NIV-pressure support ventilation (PSV). Methods: This was a prospective study of 40 patients with AECOPD given 30-min trials of NIV with NIV-PSV group (n=20) and NAVA group (n=20) in random order. Arterial blood gas analysis (ABGs), main asynchrony events and asynchrony index were quantified. Results: There were no significant difference between the two groups on effect of gas exchange (P>0.05). Main asynchrony events during NIV-NAVA including autotriggering, ineffective efforts and double triggering were less frequent than NIV-PSV (P<0.05). The trigger delay in the NIV-NAVA group was markedly shorter than the NIV-PSV (62.20±8.91 vs 112.65±15.10)ms (P<0.001). The inspiratory/expiratory off-cycle delay was significantly shorter in the NIV-PSV group than that in the NIV-NAVA group (73.00±18.27 vs 187.95±39.24)ms (P<0.001). The occurrence of severe asynchrony (AI>10%) was also less under NAVA (P<0.05). Conclusions: Both NIV-NAVA and NIV-PSV can improve gas exchange. As compared with NIV-PSV, NIV-NAVA can reduce main asynchrony events, improve patient-ventilator synchrony in patients with AECOPD.

A prospective, randomized study of inhaled prostacyclin versus nitric oxide in patients with residual pulmonary hypertension after pulmonary endarterectomy

ObjectivesPulmonary endarterectomy (PEA) is an effective treatment for chronic thromboembolic pulmonary hypertension (CTEPH), but postoperative residual hypertension leads to in-hospital mortality. Inhaled epoprostenol sodium (PGI2) and NO are administered for pulmonary hypertension after cardiothoracic surgery. This prospective study provides the first comparative evaluation of the effects of inhaled PGI2 and NO on pulmonary hemodynamics, systemic hemodynamics, and gas exchange in patients developing residual pulmonary hypertension after PEA.MethodsThirteen patients were randomized to receive either NO (n = 6) or PGI2 (n = 7) inhalation when pulmonary hypertension persisted after weaning from cardiopulmonary bypass. Hemodynamic and respiratory variables were measured before inhalation of the agent (T0); 30 min (T1), 3 h (T2), and 6 h after inhalation (T3); and the next morning (T4). The NO dose was started at 20 ppm and gradually tapered until extubation, and PGI2 was administered at a dose of 10 ng kg−1 min−1.ResultsIn both groups, mean pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) significantly decreased over time until T4 (mean PAP: p < 0.0001; PVR: p = 0.003), while mean systemic arterial blood pressure significantly increased (p = 0.028). There were no significant between-group differences in patient characteristics, cardiac index, left atrial pressure, or ratio of arterial oxygen tension to fraction of inspired oxygen. There were no in-hospital deaths.ConclusionsBoth inhaled PGI2 and NO significantly reduced PAP and PVR without adverse effects on systemic hemodynamics in patients who developed residual pulmonary hypertension after PEA. Inhaled PGI2 can be offered as alternative treatment option for residual pulmonary hypertension.

Effect of Thoracentesis on Intubated Patients with Acute Lung Injury

Pleural effusions occur frequently in mechanically ventilated patients, but no consensus exists regarding the clinical benefit of effusion drainage. We sought to determine the impact of thoracentesis on gas exchange in patients with differing severities of acute lung injury (ALI). A retrospective analysis was conducted on therapeutic thoracenteses performed on intubated patients in an adult surgical intensive care unit of a tertiary center. Effusions judged by ultrasound to be 400 mL or larger were drained. Subjects were divided into groups based on their initial P:F ratios: normal >300, ALI 200 to 300, and acute respiratory distress syndrome (ARDS) <200. Baseline characteristics, physiologic variables, arterial blood gases, and ventilator settings before and after the intervention were analyzed. The primary end point was the change in measures of oxygenation. Significant improvements in P:F ratios (mean ± SD) were seen only in patients with ARDS (50.4 ± 38.5, P = 0.001) and ALI (90.6 ± 161.7, P = 0.022). Statistically significant improvement was observed in the pO2 (31.1, P = 0.005) and O2 saturation (4.1, P < 0.001) of the ARDS group. The volume of effusion removed did not correlate with changes in individual patient's oxygenation. These data support the role of therapeutic thoracentesis for intubated patients with abnormal P:F ratios.